Why you should contract test your Microservices

Communication in Microservices is THE most important item for the exchange of data. Break one communication link unintentionally and feel the ripple effects across the system. But what if there is a way to detect communication breakage before a change is even merged into the codebase?

Communication and Integration are the backbones of MicroServices architecture. A standalone microservice cannot work in isolation without exchanging some level of information with other services, be it in the form of read or write operations. Every service in Microservice architecture depends on and communicates with one or more services. In HTTP terms, this happens via API calls.

How can it be ensured that APIs work as expected across different services? One way to do so: set up a test infrastructure during the deployment pipeline and run a set of integration or end-to-end tests. Sounds simple? Setting up a production-like infrastructure is both costly and time-consuming. Generally, these tests run late in the deployment pipeline after the code merge, not giving the author any feedback on the integration failure. But what if I told you, there is another way to do this? A way that flags and detects the integration failure very early and can help avoid communication breakages across the system. That’s where consumer-driven contract testing comes into the picture.